Deep brain stimulation (DBS) is one method that can be used to treat Parkinson's disease. In DBS, a periodic stimulation signal is injected into the brain via an implanted electrode. Depending on the location of the stimulation probe and on the strength and shape of the stimulation signal, positive clinical results can be achieved.
To determine the location of the stimulation electrode, electrophysiological data is acquired during brain surgery using recording and stimulation devices. For example, a recording microelectrode and/or a stimulation electrode can be positioned within the brain. The recording microelectrode measures the electrical activity of neurons over a representative period of time and at a number of different positions within the brain, while the stimulation electrode is used to trigger activity of specific neurons in the brain and to measure the stimulated effect on the patient. This can be achieved by applying periodic electrical stimulation signals via the stimulation electrode to different positions within the brain. Depending on the strength, shape and location of the signal, the patient can have various responses, such as visual, speech, motor effects, and/or changes of Parkinson's symptoms, as well as conditional changes of the patient. The responses can be physically observed on and in cooperation with the patient and documented together with the responsible stimulation parameters.
The acquired data (stimulation and recording results) are analyzed by a neurologist and/or electrophysiologist, who localizes specific functional areas within the patient's brain. The neurologist and/or electrophysiologist determines the correlation between the recorded neuronal activity, specific stimulation effects, the position of the applied stimulation signal within the patient's brain, and the strength of the applied stimulation signal. Based on the data, an optimum location of the implanted electrode is identified. As used herein, an optimum location is a location that achieves the most sufficient clinical result for the patient. This includes a low severity of undesired stimulation side effects, e.g., numbness or parasthesia, while providing a high-degree of desired stimulation effects, e.g., tremor, rigor and akinesia improvement. Due to the large variation of observed electrophysiological aspects, a sufficient data assessment and visual evaluation of all data becomes very important.
Conventionally, electrophysiological data is intra-operatively recorded using paper protocols and processed post-operatively using standard tools, e.g., Microsoft Excel or Access, to obtain visual representations for each type of electrophysiological data. Each type of electrophysiological data may be represented graphically, such as a snapshot bitmap of a signal recording in relation to MR anatomy or a graph showing stimulation threshold in relation to stereotactic position. Processing the different types of data individually is useful for post-operative studies. However, such processing techniques are of little value for intra-operative decision making.